Videonystagmography (VNG) is a type of testing used to assess vestibular and central nervous system function through the use of eye movement tracking, specifically evaluating
nystagmus
Nystagmus is a condition of involuntary (or voluntary, in some cases) Eye movement (sensory), eye movement. People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in visual impairment, re ...
.
The older version of technology used to perform these tests, known as
electronystagmography
Electronystagmography (ENG) is a diagnostic test to record involuntary movements of the eye caused by a condition known as nystagmus. It can also be used to diagnose the cause of vertigo, dizziness or balance dysfunction by testing the vestibul ...
(ENG), leverages electrophysiological signals.
There is a battery of tests
which can be performed using this technology and testing, typically performed by an
audiologist
Audiology (from Latin 'to hear'; and from Greek branch of learning , ''-logia'') is a branch of science that studies hearing, balance, and related disorders. Audiologists treat those with hearing loss and proactively prevent related damage. By ...
.
These tests can be diagnostic in nature or used to monitor rehabilitation. The testing typically takes place in a dark or dimmed room with the patient laying or sitting, depending on the test, on a table or chair that can lean back to a flat position.
The patient wears goggles containing a camera that tracks the pupils using infrared imaging; the video eye-tracking system records and sends pupil movement tracings to a computer typically with VNG analysis software.
The goggles may also have a cover in order to deny vision for some tests while still recording eye movement. There may be some kind of screen or light bar used to present visual stimuli, though providers may use other kinds of visual stimuli for portions of the testing. VNG can determine whether
dizziness
Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to Balance disorder, disequilibrium or a non-specific feeling, such as giddiness or foolishness.
Dizziness is a ...
is caused by inner ear disease, particularly
benign paroxysmal positional vertigo
Benign paroxysmal positional vertigo (BPPV) is a disorder arising from a problem in the inner ear. Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head.
* ...
(BPPV), as opposed to some other cause such as
low blood pressure or
anxiety
Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
.
Key Hearing (clinical practice)
VNG testing is made up of several components.
Another portion of the test requires the patient to sit in several different positions, such as lying flat staring up, head to the right, head to the left, body rolled to the right, and body rolled to the left.
The final part of the VNG requires caloric response testing.
Oculomotor testing
Gaze
Gaze testing is performed to assess for spontaneous nystagmus
Nystagmus is a condition of involuntary (or voluntary, in some cases) Eye movement (sensory), eye movement. People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in visual impairment, re ...
, meaning a nystagmus present in the absence of. visual or vestibular stimulation.
Smooth pursuit/Tracking
Smooth pursuit testing has the patient follow a visual target from left to right or up to down.
Saccades
Saccades evaluate voluntary saccadic movement, which are quick eye movements to a target.
Optokinetic test
Optokinetic testing assesses a response that occurs when trying to stabilize focus on a target while the visual field itself is moving (due to the person's head moving);
References
{{reflist
Ear procedures